This invention relates to devices for charging or recharging electric batteries and particularly a universal battery recharger for batteries having different charging characteristics.
Electric batteries are utilized to provide mobility to a great number of devices powered by electric motors or which otherwise utilize electricity. In some such devices, such as automobiles, the device provides a recharging circuit to the battery so that the battery is kept at a full level of charge as long as the recharging circuit is operative. However, it is a frequent occurence that components of the device, such as the headlights of an automobile, are inadvertantly left powered and when the charging circuit is not resupplying charging voltage. Consequently, the battery drains off most of its energy until it is recharged by an external circuit. Many other devices, such as golf carts, forklift vehicles, and numerous other portable devices are designed to draw their power from the battery without replacing the power by a charging circuit during the operation of the device. Typically, in such devices, the device is operated for a period of time and when the device is not in operation the battery is connected to an external source of power, such as a battery charger to recharge the battery. Consequently, there is a considerable need for battery charging devices to recharge batteries which either through design or inadvertance have become discharged.
It is known to provide battery charges which apply a potential voltage having a direct current across the battery terminals for a period of time. The cells of the battery absorb and store a portion of the energy provided thereby. Different types of batteries have different charging characteristics. Accordingly, a charging circuit which is designed for a particular type of battery may not function efficiently or at all as a recharger for a different type of battery or even for the same type of battery manufactured by different manufacturers. Accordingly, it is known to develop a discrete circuit which provides a charging current to a battery in a charging profile which matches the battery specification.
A battery charging profile or characteristic preferably includes three or more phases during which varying amounts of current and/or voltage are supplied to the battery. One typical recharging sequence comprises a first phase in which a constant current is provided to the battery terminals until the battery voltage is brought up to the full rated level. Once the voltage has been brought up to level, a constant voltage or current may be provided to the battery for a period of time which is often related to the period of time which elapsed during the first phase, for example a period of time equal to twice the period of time taken to bring the voltage up to its rated level. Upon the completion of the second phase, a small current is applied across the battery terminals to maintain the charge at its maximum, this third phase is sometimes called a "trickle" charging phase.
The precise time, voltage, and current which should optimally be applied to a particular battery type to recharge it often varies from one battery type to another. However, many battery users do not wish to operate plural battery rechargers, one for each type of battery and operate a battery charger having a "typical" or "average" charging characteristics. However, such an "average38 battery charger may not meet the desired charging characteristics of any of the batteries on which it is utilized.
Accordingly, it is an object of the present invention to provide a battery charging method and apparatus which can efficiently recharge many different types of batteries.
It is a further object of the present invention to provide a battery charging method and apparatus in which different types of batteries may be recharged without the necessity of changing the components of the charger except for a charging characteristic memory.
It is yet a further object of the present invention to provide a battery charging method and apparatus for charging batteries having both low sulfation and high sulfation characteristics.
It is yet another object of the present invention to provide a novel battery charging method and apparatus which will charge batteries having charging characteristics which are currently unknown or unanticipated.
The invention will now be described in more detail by way of example with reference to the accompanying drawings in which: